gi

GoGi is part of the GoKi Go language (golang) full strength tree structure system (ki = tree in Japanese)

package gi is a scenegraph-based 2D and 3D GUI / graphics interface (Gi) in Go

NOTE: Requires Go version 1.10+ due to use of math.Round.

See the Wiki for more docs, discussion, etc.

GoGi uses the GoKi tree infrastructure to implement a simple, elegant GUI framework in full native idiomatic Go (with minimal OS-specific backend interfaces based on the Shiny drivers). The overall design is an attempt to integrate existing standards and conventions from widely-used frameworks, including Qt (overall widget design), HTML / CSS (styling), and SVG (rendering). This 2D framework also integrates with a (planned) 3D scenegraph, supporting interesting combinations of these frameworks. Currently GoGi is focused on desktop systems, but nothing prevents adaptation to mobile.

Main Features

• Has all the standard widgets: Button, Menu, Slider, TextField, SpinBox, ComboBox etc, with tooltips, hover, focus, copy / paste (full native clipboard support), drag-n-drop -- the full set of standard GUI functionality. See gi/examples/widgets for a demo.

• Powerful Layout logic auto-sizes everything -- very easy to configure interfaces that just work across different scales, resolutions, platforms. Automatically remembers and reinstates window positions and sizes across sessions.

• CSS-based styling allows easy customization of everything -- native style properties are fully HTML compatible (with all standard em, px, pct etc units), including full HTML "rich text" styling for all text rendering (e.g., in Label widget) -- can decorate any text with inline tags (<strong>, <em> etc), and even include links.

• Compiles in second(s), compared to hour(s) for Qt, and is fully native with no cgo dependency on Linux and Windows, and minimal cgo (necessary) on MacOS.

• Fully self-contained -- does not use OS-specific native widgets -- results in simple, elegant, consistent code across platforms, and is fully HiDPI capable and scalable using standard Shift+Ctrl/Cmd+Plus or Minus key, and in Preferences (press Ctrl+Alt+P in any window to get Prefs editor).

• SVG element (in svg sub-package) supports full SVG rendering -- used for Icons internally and available for advanced graphics displays -- see gi/examples/svg for viewer and start on editor, along with a number of test .svg files.

• Advanced Model / View paradigm with reflection-based view elements that display and manipulate all the standard Go types (in giv sub-package), from individual types (e.g., int, float display in a SpinBox, "enum" const int types in a ComboBox chooser) to composite data structures, including StructView editor of struct fields, MapView and SliceView displays of map and slice elements (including full editing / adding / deleting of elements), and full-featured TableView for a slice-of-struct and TreeView for GoKi trees.

  • TreeView enables a built-in GUI editor / inspector for designing gui elements themselves. Just press Control+Alt+I in any window to pull up this editor / inspector. Scene graphs can be automatically saved / loaded from JSON files, to provide a basic GUI designer framework -- just load and add appropriate connections..

Code Map

• examples/widgets -- main example widget gallery -- go get ... go build in there to give it a try -- see README there for more info. Many other demos / tests in examples/*.
• node*.go -- NodeBase, Node2DBase, 3D structs and interfaces -- all Gi nodes are of this type.
• geom2d.go -- Vec2D is main geom type used for 2D, plus transform Matrix2D.
• paint.go -- Paint struct that does all the direct rendering, uses gg-based API but now uses the srwiley/renderx rendering system which supports SVG 2.0, and is very fast.
  • stroke.go, fill.go -- StrokeStyle and FillStyle structs for stroke, fill settings
  • color.go -- ColorSpec for full gradient support, Color is basic color.Color compatible RGBA type with many additional useful methods, including support for HSL colorspace -- see Wiki Color for more info.
• style.go -- Style and associated structs for CSS-based Widget styling.
• viewport2d.go -- Viewport2D that has an Image.RGBA that Paint renders onto.
• window.go -- Window is the top-level window that manages an OS-specific oswin.Window and handles the event loop.
  • oswin is a modified version of the back-end OS-specific code from Shiny: https://github.com/golang/exp/tree/master/shiny -- originally used https://github.com/skelterjohn/go.wde but shiny is much faster for updating the window because it is gl-based, and doesn't have any other dependencies (removed dependencies on mobile, changed the event structure to better fit needs here).
• font.go, text.go -- FontStyle, TextStyle, and TextRender that manages rich-text rendering in a powerful, efficient manner (layered on RuneRender and SpanRender). FontStyle contains the global color, background-color, and opacity values, to make these easily avail to the TextRender logic.
• layout.go -- main Layout object with various ways of arranging widget elements, and Frame which does layout and renders a surrounding frame.
• widget.go -- WidgetBase for all widgets.
• buttons.go -- ButtonBase, Button and other basic button types.
• action.go -- Action is a Button-type used in menus and toolbars, with a simplified ActionSig signal.
• bars.go -- MenuBar and ToolBar
• sliders.go -- SliderBase, Slider, ScrollBar.
• textfield.go for TextField, label.go for Label, etc -- also defines the gi.Labeler interface and ToLabel converter method (which falls back on kit.ToString using Stringer), which is used for generating a gui-appropriate label for an object -- e.g., for reflect.Type it just presents the raw type name without prefix.
• icon.go for Icon wrapper around svg icons (in svg sub-package)
• Sub-packages:
  • svg -- has all the SVG nodes (Path, Rect etc) plus io.go parser
  • giv -- has all the *View elements
  • gimain -- provides a meta-package wrapper to simplify imports for main apps -- also does relevant final platform-specific customization
  • units -- CSS unit representation

Code Overview

There are three main types of 2D nodes:

• Viewport2D nodes that manage their own oswin.Image bitmap and can upload that directly to the oswin.Texture that then uploads directly to the oswin.Window. The parent Window has a master Viewport2D that backs the entire window, and is what most Widget's render into. + Popup Dialog and Menu's have their own viewports that are layered on top of the main window viewport. + SVG and its subclass Icon are containers for SVG-rendering nodes.

• Widget nodes that use the full CSS-based styling (e.g., the Box model etc), are typically placed within a Layout -- they use units system with arbitrary DPI to transform sizes into actual rendered dots (term for actual raw resolution-dependent pixels -- "pixel" has been effectively co-opted as a 96dpi display-independent unit at this point). Widgets have non-overlapping bounding boxes (BBox -- cached for all relevant reference frames).

• SVG rendering nodes that directly set properties on the Paint object and typically have their own geometry etc -- they should be within a parent SVG viewport, and their geom units are determined entirely by the transforms etc and we do not support any further unit specification -- just raw float values.

General Widget method conventions:

• SetValue kinds of methods are wrapped in UpdateStart / End, but do NOT emit a signal
• SetValueAction calls SetValue and emits the signal This allows other users of the widget that also recv the signal to not trigger themselves, but typically you want the update, so it makes sense to have that in the basic version. ValueView in particular requires this kind of behavior.

The best way to see how the system works are in the examples directory, and by interactively modifying any existing gui using the interactive reflective editor via Control+Alt+E.

Status

Currently at a pre-beta level (DON'T RECOMMEND USING RIGHT NOW -- come back in a few weeks after announcement on go-nuts email list).

• Major push underway to get to the following target for a beta level release:

• All major functionality is in place, and API is stable and only very minor changes will be allowed going forward. The system is now ready for wider adoption.

• Everything has been thoroughly tested, but generally only by a small number of core developers / users.

• Please file Issues for anything that does not work (except as noted below under TODO)

TODO

• diffs revert not updating all the way.. maybe one liners? really not sure.

• filenode: ability to sort by date within directories

• crash in + for element of split array -- in spinbox -- "up"'s .This is nil in spinbox -- is a result of fullrebuild

• drag on textview should prevent DND -- dnd not getting "processed"

• fileview keyboard shortcuts: page up / down (tableview), history prev = go up dir? history next = go to next in history list? or just pop up history list probably. maybe command-uparrow = up dir? Need something intuitive there. also a cancel? esc takes a few to actually cancel..

• TextView:

  • clicking back to other window textview fails to grab blinky cursor -- works for C-x p / o but not mouse clicking.
  • clipboard history
  • still some wordwrap issues with tabs. grr.
  • word-level functions: forward, back, delete etc. ctrl+ backspace is back.
  • cursor goes to hand for links in TextView

• Splitview:

  • gide resize textview not re-drawing (still?)

• sliceinlineview -- not passing inactive onto its constituent elements. check for other inline etc views.

• CSS class = x should bring in properties for that class into top-level CSS for all below -- not sure it does that - nested classes. need to figure that out really.

• slice of ki: do proper add so it works directly by editing children -- requires accessing owner info from valueview recs -- that is what the ki.Slice by itself does not have

• see if ubuntu and windows have a decent unicode fallback font https://unix.stackexchange.com/questions/14027/what-fonts-are-good-for-unicode-glyphs

• windows: arialuni.ttf https://docs.microsoft.com/en-us/typography/font-list/arial-unicode-ms

• textfield should scroll layout so that cursor is always in view, when editing..

• fileview should add extension to filename if only one extension provided, if user types in a new filename..

• fix text scrolling-off-top rendering finally

• fix the style-props context -- need an overall prop on objects -- in type presumably. completer needs to know about this too. in mapview proximally.

• update gi/doc.go with final readme notes etc! add docs to this README about "what can you do with demos?" kind of thing..

• update widgets README

• Reminder: grep all todo: in code